A039507 Number of odd non-cluster primes less than 10^n.

0, 1, 68, 808, 7784, 70210, 624561, 5559246, 49787726, 449315793, 4086143347, 37425892724, 345004813781

Offset: 1

Author

Christian G. Bower, Feb 15 1999

Keywords

• nonn
• more

Comments

The Blecksmith paper gives incorrect values of a(n) for n>8. - T. D. Noe, Jul 21 2006

Links

• Richard Blecksmith, Paul Erdős and J. L. Selfridge, Cluster Primes, Amer. Math. Monthly, 106 (1999), 43-48.
• Eric Weisstein's World of Mathematics, Cluster Prime.
• Wikipedia, Cluster prime.
• Index entries for sequences related to numbers of primes in various ranges

Crossrefs

Cf. A038133, A038134, A039506.

Formula

a(n) = A006880(n) - A039506(n) - 1. - T. D. Noe, Jul 21 2006

Extensions

Corrected by T. D. Noe, Jul 21 2006